One serious problem with using murine antibodies for therapeutic applications in humans is that they quickly raise a human anti-mouse response (HAMA) which reduces the efficacy of the antibody in patients, and prevents continued administration thereof. Parallel issues arise with the administration of antibodies from other, non-human species. One approach to overcoming this problem is to generate so-called “chimeric” antibodies. These can comprise murine variable regions, and human constant regions (Boulianne et al. (1984) Nature 312(5995): 643-646.; incorporated by reference herein in its entirety). Although chimeric antibodies contain murine sequences and can elicit an anti-mouse response in humans (LoBuglio et al. (1989) Proc. Natl. Acad. Sci. USA 86(11): 4220-4224; incorporated by reference herein in its entirety), trials with chimeric antibodies in the area of hematological disease (e.g., Non-Hodgkin-Lymphoma; Witzig et al. (1999) J. Clin. Oncol. 17(12): 3793-3803; incorporated by reference herein in its entirety) or autoimmune disease (e.g., rheumatoid arthritis, chronic inflammatory bowel disease; Van den Bosch; et al, Lancet 356(9244):1821-2 (2000), incorporated by reference herein in its entirety) have led to FDA approval and demonstrate that these molecules have significant clinical potential and efficacy.
Recent studies have indicated that granulocyte-macrophage colony stimulating growth factor (GM-CSF) plays a role in the development of rheumatoid arthritis (RA) (Cook, et al., Arthritis Res. 2001, 3:293-298, incorporated by reference herein in its entirety) and possibly other inflammatory diseases and conditions. Therefore, it would be of interest to develop a drug which would block GM-CSF and its effect on cells. The present invention provides a chimeric antibody, targeting the GM-CSF molecule, which has blocking capacity.
The increased use of chimeric antibodies in therapeutic applications has created the need for expression vectors that effectively and efficiently produce high yields of functional chimeric antibodies in eukaryotic cells, such as mammalian cells, which are preferred for production. The present invention provides novel expression vectors, transformed host cells and methods for producing chimeric antibodies in mammalian cells, as well as the antibodies themselves and fusion proteins containing them.